lifter trouble

all this engine oil talk,,i didnt know that gas engine oil has changed,,shell rotella is 15/40,,i cant imagine how much oil pressure ide have with that heavy oil,i use that in my cumins dodge,,,and 30 sae in my cuda,,,straight weight was once upon a time recomended by mopar racing manual.

i have a colapased lifter in my 241 ci dodge hemi in my street rod,,,my next project comming up,,,pull it apart and change the lifters,,and maybe adjustable push rods,,,rotella oil????? stp??? for zinc????

excuse me for knot knowing,,,but some one clue me in on this stp for zinc ?or rotella????? or where i can read on it please,...

e mail me please [email protected] thanks don